Apple is working on other charging methods for the iWatch; it has experimented with wireless inductive charging similar to that found in some Nokia Lumia smartphones. A 2009 patent reveals that Apple has also experimented with motion charging, using the kinetic energy of the wearer's swinging arm to top up the iWatch's battery.

Battery life is the single biggest challenge faced by wearable tech manufacturers – where the Pebble smartwatch has got around the issue by keeping things simple, more sophisticated smartwatches like the Samsung Galaxy Gear require daily charging.

If Apple's planning to bring an innovative, feature-packed iWatch to market, it needs to crack the issue of how to keep it charged for long periods of time – and we may have some time to wait before we can wrap it around our wrists.